Rugby union and rugby league cross-code pioneer Peter Ryan wants to make it "unpleasant" for opposition teams to play against the ACT Brumbies next season.

He has agreed to join Stephen Larkham's coaching roster.

The former Brumbies championship winner and Brisbane Broncos premiership player will replace Laurie Fisher on the ACT staff, which means Larkham has all but finalised his coaching structure for the 2015 Super Rugby campaign.

Former Wallabies prop Dan Palmer will also work as a scrum coach during the pre-season.

After almost 10 years out of rugby, Ryan will take charge of the collision zone and fine-tune the Brumbies' breakdown work and tackling techniques.

"I want the opposition to realise they're being tackled, we want an attitude in our defence and our contact so that it's unpleasant for teams to play against the Brumbies," Ryan said.

"I think my personality can give this to the Brumbies. I appreciate the opportunity to do it and I think it's a step in the right direction.

"The teams that win Super Rugby titles, they're the best defensive teams. The more desperate you are in that, the better you are."

Ryan was the first player to win grand finals in the NRL and Super Rugby.

Described by Melbourne Storm coach Craig Bellamy as "one of the most devastating defenders" in rugby league, Ryan played for the Broncos from 1989 to 1999.

He switched codes to join the Brumbies and won a Super Rugby title in 2001 before finishing his playing career in Japan.

Ryan has had coaching stints at the Broncos and the North Queensland Cowboys. He says the timing is right for a return to rugby.

"I've made a bit of a habit of switching," Ryan said. "I think it's like tennis and squash – similar but completely different.

"I'll have to brush up on the rules more ... But it blends well for me. Rugby league has been great to me through my life and rugby has been similar.

"I haven't attacked rugby at a coaching level ... it seemed like the right time."

Larkham hopes to appoint a team manager in the coming weeks to replace the outgoing Tony Thorpe.

Fisher's decision to join English club Gloucester left a hole in the Brumbies coaching ranks.

Fisher is regarded by many as one of the best forwards coaches in the world.

Larkham is still defining all of the coaching roles in his first season as the head coach. He shared the job with Fisher last season.

Ryan will join Larkham and Dan McKellar. Palmer will act as a scrum consultant during the pre-season.

"He was a tough character when he was playing here ... he's the right fit for the coaching set up we have here," Larkham said of Ryan.

"He's a no-nonsense talker and expects quality all the time. He'll do anything to do with the contact area – tackling technique, ball carry, breakdown and defence."

Ryan will move to Canberra in November for the start of pre-season training.